Advances in electronics have resulted in an increasing number of functions and capabilities being realized by semiconductor devices, for example, integrated circuits (ICs), such as microcontroller units (MCUs). To provide those functions and capabilities, semiconductor devices, such as MCUs, continue to include an increasing number of transistors.
To reduce cost and yet meet the specifications for more functions and capabilities, semiconductor technology has continued to drive the trend towards higher device density and smaller device geometries. Circuit techniques have also eliminated or reduced the use of several power supplies, such as bipolar power supplies (i.e., providing both positive and negative supply voltages). As a result, some ICs, such as typical MCUs, operate from a single positive supply voltage.